Noble Gases
Group 18 elements have full shells and rarely react.
About this topic
The noble gases (group 18: He, Ne, Ar, Kr, Xe, Rn) have full outer shells, making them very stable and almost unreactive. They exist as single atoms (monatomic), are colourless and odourless, and have very low boiling points that rise down the group.
Because the outer shell is full, they have no tendency to gain, lose or share electrons, and their atoms attract each other only through weak dispersion forces. Their stability explains the octet rule that other elements follow when bonding. Argon makes up about 0.93 percent of air and is the third most abundant gas. Chemists did eventually make compounds of xenon and krypton with fluorine in the 1960s, showing that no rule is absolute.
Helium fills balloons, being safe and lighter than air, and cools MRI magnets. Neon glows red-orange in signs, argon provides an inert atmosphere for welding and inside light bulbs, and xenon is used in headlights and ion engines. Radon is radioactive and can build up in basements, so homes may need testing.
A common mistake is calling them inert, which suggests no compounds exist; unreactive is more accurate. Also, helium has only two valence electrons but still has a full first shell. The name noble comes from their aloofness.
Key ideas
- Helium, neon, argon …
- Stable octets
- Used in lighting and balloons
Quick check
Use cases: where Noble Gases helps
- Homework: review the key idea behind Noble Gases before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Noble Gases without notes.
- Visual learning: play with the interactive lab to see how Noble Gases changes when you adjust its inputs.
- Teaching a friend: explain Noble Gases in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Noble Gases?
Group 18 elements have full shells and rarely react.
What will I learn in Noble Gases?
Helium, neon, argon …. Stable octets. Used in lighting and balloons.
Is Noble Gases part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Noble Gases lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Noble Gases?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.